Online social networks connect users with common interests to each other. Social networking sites such as Myspace.com, Friendster.com, Tribe.net, and Orkut.com foster relationships between their members, thereby offering a higher level of affiliation and trust than other online media through which users can interact with each other such as electronic message boards or forums.
These and other social networks have witnessed tremendous growth by offering users unique opportunities for self-expression, socialization, and the distribution of user-made content. The proliferation of social network objects such as users, communities, postings, and other forms of content, however, has exacerbated the challenge of identifying relevant and high-quality content. Existing search interfaces within social networks leave much to be desired. While results may be returned based on word matches or user ratings, for instance, other ways to assess the importance or quality of objects found is generally lacking. As a result, a user may be required to view many low-quality and unwanted items before finding a social network object of interest. Conventional methods of ranking webpages also have their shortcomings when applied to social networks. They generally rely solely on measures of value extrinsic to an online social network such as the location and frequency of keywords on a particular page. These metrics, however, do not by themselves reflect the value of an object in a social network.